The present invention relates generally to robot systems used for automated assembly, and more specifically to an adjustable micromanipulator that may be interposed between the fingers and the remainder of a robotic arm's structure for increasing the accuracy with which an arm's fingers may be positioned.
Mechanical devices capable of mimicking operations which may be performed by a human arm and hand, frequently referred to as "robotic arms" or "manipulators", are well known. Motion is frequently induced in a robotic arm by rotating it about a joint located near one of its ends which is commonly referred to as the arm's "shoulder." The other end of such a robotic arm, the end which translates when the arm rotates about its shoulder, is frequently referred to as its "hand". The parts of such hands which are used to grasp or manipulate an item are frequently referred to as its "fingers". To control the positioning of an arm's fingers, an arm generally includes other joints distributed along its length between its shoulder and its fingers which may provide either rotary or translational motion.
Such robotic arms are routinely capable of translating their hands throughout a relatively large volume, e.g. 1 cubic meter or more. However, within that large operating volume it is also frequently desirable to accurately position the hand's fingers, e.g. with a permissible error of much less than 1 mm. Because of the distance separating the location at which an arm's gross motions originate, i.e. its shoulder, and its fingers, minute errors at the source of such motion are magnified by the arm's length. Further, the elasticity of the arm's mechanisms and the arm's inherent flexibility introduce further static and dynamic errors in positioning its hands or fingers. In general, as the ratio of the range of an arm's gross motions to its finger position accuracy increases, it becomes progressively more and more difficult to accurately control the position of an arm's fingers. Inadequate finger position accuracy is obtained merely by controlling the arms movement about its shoulder or at other joints located near the shoulder.
The task of providing a means of adjusting the position of finger elements of robot arm systems is alleviated to some extent, by the systems of the following U.S. Patents, the disclosures of which are incorporated herein by reference:
U.S. Pat. No. 4,595,334 issued to Sharon; PA1 U.S. Pat. No. 4,300,362 issued to Lande et al; PA1 U.S. Pat. No. 4,435,116 issued to Van Deberg; PA1 U.S. Pat. No. 3,784,031 issued to Niitu et al; and PA1 U.S. Pat. No. 4,144,947 issued to Pittwood.
U.S. Pat. No. 4,595,334 discloses a robotic apparatus having five degrees of movement, and first, second, and third stage platforms to move and rotate the apparatus.
U.S. Pat. No. 4,300,362 discloses an articulation for a manipulator which includes two supporting elements interlinked by at least two connecting rods, the ends of which are coupled with the supporting elements by joints with two degrees of freedom.
U.S. Pat. Nos. 4,435,116, 3,784,031, and 3,144,947 each disclose a robotic manipulator for handling objects.
While the systems of the above-cited references are instructive, a need remains to provide a means for increasing the accuracy in which a robot arm's fingers may be positioned. The present invention is intended to satisfy that need.